The document discusses different methods for visualizing data distributions, including histograms and stem-and-leaf displays. It provides examples of histograms of earthquake magnitudes, including a regular histogram showing counts in bins and a relative frequency histogram showing percentages. It also explains that stem-and-leaf displays show the distribution of a quantitative variable while preserving individual values.

1. Slide 4- 1
Histograms: Earthquake Magnitudes
• The chapter example discusses earthquake
magnitudes
• First, slice up the entire span of values covered
by the quantitative variable into equal-width
piles called bins.
• The bins and the counts in each bin give the
distribution of the quantitative variable.

2. Slide 4- 2
Histograms: Earthquake Magnitudes (cont.)
• A histogram plots the bin
counts as the heights of bars
(like a bar chart).
• Here is a histogram of
earthquake magnitudes

3. Slide 4- 3
Histograms: Earthquake Magnitudes (cont.)
• A relative frequency histogram displays the percentage of
cases in each bin instead of the count.
– In this way, relative
frequency histograms are
faithful to the area
principle.
• Here is a relative frequency
histogram of
earthquake magnitudes:

4. Slide 4- 4
Stem-and-Leaf Displays
• Stem-and-leaf displays show the distribution
of a quantitative variable, like histograms do,
while preserving the individual values.
• Stem-and-leaf displays contain all the
information found in a histogram and, when
carefully drawn, satisfy the area principle and
show the distribution.

5. Slide 4- 5
Stem-and-Leaf Example
• Compare the histogram and stem-and-leaf display for the
pulse rates of 24 women at a health clinic. Which graphical
display do you prefer?